Hadley Telescope Azimuth Bearing

This is an azimuth bearing for the Hadley telescope that uses a PTFE bowden tube as a low friction interface material. Bowden tubes are inexpensive and readily available, making them an ideal source of PTFE material for the bearing.

The tube sits in a V-groove. The centerline of the groove is 150mm in diameter so the bowden tube must not be longer than 471mm; leave it a little shorter than that. I used a 4mm OD, 2mm ID bowden tube. To help the tube hold it's shape and stay in the groove when assembling the telescope, place a length of filament into the tube connecting each end (see second picture).

Print Settings:

• This isn't a high-stress part so default print settings are probably fine, except as noted below.
• Grid infill is probably preferable because it's denser at a given infill % and is aligned with the direction of loading.
• You can reduce print time by approx. 25% by using zero bottom layers.
• IMPORTANT: there is a flared section of the groove which is meant for the z-seam so the tube won't catch on it. Make sure the z-seam is located in that flare (see third picture). In Cura, set “Z Seam Alignment” to “Sharpest Corner”. A little bit of manual touch-up with a hobby knife may be needed to get a nice smooth transition.

You will need to print two of these; one for the top raceway, one for the bottom.